Neutron detectors may be used to monitor radioactive sources that emit neutrons. They may be used for medical imaging, neutron radiography, high resolution images and for detecting radioactive materials that may be hidden from sight (e.g., being smuggled through a security checkpoint).
One conventional neutron detector system utilizes a device known as a Schottky barrier. The Schottky barrier includes a metal layer on a gallium arsenide (GaAs) semiconductor material and a neutron sensitive surface layer, such as 10B. A negative voltage applied at a first metal contact sets up the Schottky barrier. The combination of the negative voltage at the first metal contact and positive voltage applied at a second metal contact creates an electric field in the GaAs material which results in an active GaAs region. Incident neutrons react with neutron absorbing atoms in the neutron sensitive surface layer (e.g., 10B) to form energetic particles (e.g., alpha (4He) and 7Li). One of the charged particles from the reaction will penetrate through the neutron sensitive surface layer and the Schottky barrier and enter the active region of the GaAs semiconductor. In the active GaAs active region, the energetic particle gives up some of its energy to form electron hole pairs. These charged carriers (the electrons and the holes) then move in the electric field and create a current pulse which appears in an external circuit to provide for detection of neutrons.
Another conventional neutron detector system utilizes a microchannel plate made of glass doped with 10B. The microchannels are aligned normal to the surface of the plate and include a high resistance material. A high voltage is applied between the two faces of the plate. Incoming neutrons react with the 10B in the solid bulk of glass of the plate and generate energetic particles. The energetic particles travel through the bulk of the solid glass and hit the lining of various microchannels to generate electrons. The electrons emitted from the wall of each microchannel then hit the opposite walls of that channel to generate more electrons, which similarly hit opposite walls, and so forth, resulting in an avalanche of electrons in that microchannel. The avalanche of electrons emitted from various microchannels is each detected as a pulse by a detector, such as a cross-finger anode board. This provides information as to where and when the pulse emitted from the microchannel plate to provide for detection of neutrons.